This work
optimizes the excitation flip angle of a navigator pencil-beam to maximize
optimal liver/lung contrast while avoiding saturation artifacts in the liver.
We used an investigative navigator-gated T1-weighted 3D GRE sequence under
clinical conditions for gadoxetic acid-enhanced liver MRI in the hepatobiliary
phase. The presence of saturation artifacts and the optimal navigator flip
angle are highly dependent on the imaging flip angle and the presence of
gadolinium in the liver. Using an imaging flip angle of 30o, 20-60 minutes
after gadoxetic acid, the optimal navigator flip angle is 90o, without any
appreciable saturation artifact.